Texture embraced meniscus polymerization

ABSTRACT

A 3D printing system includes a tank containing a liquid photopolymer resin. A textured surface is disposed in the tank. The textured surface is configured such that light passes through therethrough and into the liquid polymer resin. A layer of an inert material is disposed on the textured surface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part application of U.S.application Ser. No. 17/535,540, filed Nov. 24, 2021. The entiredisclosure of U.S. application Ser. No. 17/535,540 is herebyincorporated herein by reference.

BACKGROUND Field of the Invention

The present invention generally relates to a system and method of 3Dprinting. More specifically, the present invention relates to a 3Dprinting system and method including a tank having a textured surfacethrough which light is configured to pass and a layer of an inert liquiddisposed on the textured surface.

Background Information

3D (three-dimensional) printing is the construction of athree-dimensional object from a digital file, such as a CAD model or adigital 3D model. A conventional additive manufacturing process createsthe object by successively adding layers one at a time until the objectis complete. One type of additive manufacturing process is vatpolymerization, which includes stereolithography (SLA) and digital lightprocessing (DLP) processes.

As shown in step S1 of FIG. 1 , DLP 3D printing includes a tank, or vat,10 having a transparent projection window 12. The vat 10 contains aliquid polymer resin 14. A build platform 16, on which an object is tobe printed, is lowered into the resin 14.

A light projection system 18, such as a laser, projector or LED/LCDpanel, emits a light 20, such as ultraviolet light, through thetransparent projection window 12 in the vat 10, as shown in Step S2 ofFIG. 1 . The emitted light 20 causes a reaction within the resin 14 inwhich the molecules bond together, or cure, to form a first layer of asolid object 22 on the build platform 16. The entire first layer iscured simultaneously. The build platform 16 is moved in a direction awayfrom the transparent projection window 12 to form a second laver on thefirst layer. Layers are formed, one layer at a time, until the object isprinted.

During the printing process, the polymerized resin can adhere to thetransparent projection window 12 of the vat 10, which can interfere withforming additional layers on the build platform 16. Additionally, thegap between the build platform 16 and the transparent window 12, orbetween the formed solid object 22 on the build platform 16 and thetransparent window 12 for subsequent layers, is small (e.g., a distancesubstantially equal to a thickness of one formed layer on the buildplatform). As shown in step S3 of FIG. 1 , the build platform 16 isremoved from the vat 10. Any polymerized resin adhered to thetransparent window 12 of the vat 10 can be removed, and additionalliquid polymer resin 14 can be added to the vat 10.

As shown in step S4 of FIG. 1 , the build platform 16 is lowered intothe liquid polymer resin 14 in the vat 10 until the appropriate distancebetween the printed object 22 and the transparent window 12 is obtained.The separation step of the build platform 16 from the vat 10 in step S3and repositioning the build platform 16 in the vat 10 in step S4 aretime consuming steps that slow down the DLP 3D printing process.Removing any resin adhered to the transparent window 12 further slowsdown the printing process.

A conventional 3D printing system used in the DLP 3D printing process ofFIG. 1 is shown in FIG. 2 . The light projection system 18 emits light,such as UV (ultraviolet) light, corresponding to a single image of thelayer to be formed on the build platform 16. The emitted light 20 passesthrough a projection lens 24 to adjust the resolution of the emittedlight 20. The projection lens 24 is selected based on the desired focaldepth, such as 30 or 100 micrometers. The projected light 26 istransmitted to a mirror 28. The reflected light 30 is transmitted intothe vat 10 through a transparent window 12 (FIG. 1 ) thereof. Thereflected light 30 cures the resin in the vat 10 to form a first layerof the printed object 22. A robotic arm 32 moves the build platform 16such that successive layers can be formed to construct the printedobject 22.

SUMMARY

A need exists for a 3D printing system in which adhesion between theprinted object and the window is substantially prevented. A need alsoexists for a 3D printing process in which resin flows in a timely mannertoward a gap between a printed object and a window to form a successiveresin layer to facilitate continuous photopolymerization. A further needexists for a 3D printing process facilitating resin flow.

In view of the state of the known technology, one aspect of the presentdisclosure is to provide a 3D printing system including a tankcontaining a liquid photopolymer resin. A textured surface is disposedin the tank. The textured surface is configured such that light passesthrough and into the liquid polymer resin. A layer of an inert materialis disposed on the textured surface.

Another aspect of the present disclosure is to provide a 3D printingsystem including a tank containing a liquid photopolymer resin, and arigid base on which an object is configured to be printed. A texturedsurface is disposed in the tank. The textured surface is configured suchthat light passes through and into the liquid polymer resin. A layer ofan inert material disposed on the textured surface. The resin isdisposed between the layer of the inert material and the rigid base.

Also other objects, features, aspects and advantages of a 3D printingsystem and method will become apparent to those skilled in the art fromthe following detailed description, which, taken in conjunction with theannexed drawings, discloses exemplary embodiments of the 3D printingsystem and method.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a schematic representation of a conventional 3D printingsystem and method;

FIG. 2 is a perspective view of a conventional 3D printing system ofFIG. 1 ;

FIG. 3 is a side elevational view of a 3D printing system in accordancewith an exemplary embodiment;

FIG. 4 is a side elevational view of a 3D printing system in accordancewith another exemplary embodiment;

FIG. 5 is an elevational view of the 3D printing system of FIG. 3illustrating a resin flow path generated by a transducer:

FIG. 6 is a perspective view of a tank of the 3D printing system of FIG.3 ;

FIG. 7 is an elevational view of the tank of FIG. 6 ;

FIG. 8 is an elevational view of a tank of a 3D printing system inaccordance with another exemplary embodiment in which a transducer isconnected to an upper portion of a tank;

FIG. 9 is a side elevational view of the tank of FIG. 8 ;

FIG. 10 is a perspective view of a 3D printing system in accordance withyet another exemplary embodiment in which a plurality of transducers aremounted to a tank;

FIG. 11 is a top plan view of the tank of FIG. 10 ;

FIG. 12 is a schematic representation of an inert layer disposed on atextured surface of the tank of FIG. 3 ;

FIG. 13 is a schematic representation of speeds at which acoustic wavesgenerated by a transducer travel through the inert layer and the resinof FIG. 12 ;

FIG. 14 is a side elevational view of the textured surface of the tankof FIG. 3 having a hydrophobic coating;

FIG. 15 is a top plan view of the textured surface of the tank of FIG. 3;

FIG. 16 is side elevational view of the textured surface of FIG. 15 ;

FIG. 17 is a side elevational view of the textured surface of FIG. 15having hydrophobic nanostructures:

FIG. 18 is a side elevational view of a textured surface in accordancewith another exemplary embodiment;

FIG. 19 is a side elevational view of the textured surface of FIG. 18having hydrophobic nanostructures; and

FIG. 20 is a side elevational view of a 3D printing system in accordancewith another exemplary embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Selected exemplary embodiments will now be explained with reference tothe drawings. It will be apparent to those skilled in the art from thisdisclosure that the following descriptions of the exemplary embodimentsare provided for illustration only and not for the purpose of limitingthe invention as defined by the appended claims and their equivalents.

Referring initially to FIG. 3 , a 3D printing system 110 in accordancewith an exemplary embodiment includes a tank 112, a textured surface 114connected to the tank 112, and a first transducer 116 configured to emitan acoustic wave 118 toward the textured surface 114. The 3D printingsystem 110 further includes a rigid base 120 on which an object 122 isto be printed and a control arm 124 connected to the rigid base 120.

The rigid base 120 has a print surface 120A on which the object 122 isconfigured to be printed, as shown in FIG. 3 . The control arm 124 isconnected to the rigid base 120 to move the rigid base 120 relative tothe tank 112. The first transducer 116 is connected to the tank 112 andis configured to emit the first acoustic wave 118 toward the texturedsurface 114. A light source 126 is configured to emit light 128 to thetank 112 to form the printed object 122 on the rigid base 120.

The tank 112 contains a liquid photopolymer resin 130, as shown in FIGS.3 and 6-8 . The tank 112 can be any suitable shape to hold the liquidpolymer resin 130 therein, such as rectangular or circular. The tank 112has a base 132 and a side wall 134 extending upwardly from the base 130.The base 132 is preferably transparent such that the light 128 emittedfrom the light source 126 can pass through the base 132. The entirety ofthe base 132 can be transparent, or a portion of the base 132 can betransparent. The transparent portion of the base 132 constitutes anoptically transparent window 132A through which the emitted light 128can pass.

The rigid base, or build platform, build plate or print bed, 120provides the surface 120A on which the object 122 is printed. The printsurface 120A is preferably a planar surface, as shown in FIG. 3 . Therigid base 120 can be made of any suitable material, such as plastic,such as polylactic acid (PLA), or glass.

The control arm 124 is connected to the rigid base 120 to controlmovement and positioning of the rigid base 120 during the printingprocess. The control arm 124 is connected to the rigid base 120 to movethe rigid base 120 relative to the tank 112. The control arm 124preferably has six degrees of freedom, such that the rigid base 120 canmove through a curvilinear path to more accurately print the object 122.The control arm 124 is preferably a robotic arm having six degrees offreedom. The six degrees of freedom are movements along the three axes(i.e., the X, Y and Z axes), and rotation about each of the three axes(i.e., pitch, roll and yaw). Providing the control arm 124 with multipledegrees of freedom, such as six degrees of freedom, allows the controlarm 124 to move the rigid base 120 through a curvilinear path, includingmoving the rigid base 124 to a plurality of positions, thereby allowinga more accurate object 122 to be printed.

The liquid polymer resin 130 is selectively cured by light-activatedpolymerization, such as by photopolymerization, which preferably usesvisible or UV light, although light having any suitable wavelength canbe used, to form in situ cross-linked polymer structures. The liquidpolymer resin 130 preferably includes monomer and oligomer moleculesthat are converted to solid polymers during photopolymerization when thelight 128 emitted by the light source 126 is guided through thetransparent portion, or the optically transparent window 132A, of thebase 132 of the tank 112.

The light source 126 emits light 128 to cure the liquid polymer resin130 in the tank 112, as shown in FIG. 3 . The light source 126preferably emits UV light 128 having a wavelength between approximately10 and 400 nanometers, inclusive. Preferably, the emitted UV light 128has a wavelength between approximately 380 and 400 nanometers,inclusive. Light having any suitable wavelength can be used, such as,but not limited to, UV, visible and infrared light.

The liquid polymer resin 130 includes a photoinitiator that initiatesphotopolymerization in the tank 112 when the light 128 emitted by thelight source 126 passes through the optically transparent window 132A ofthe base 132 of the tank 112. The photoinitiator absorbs light energyhaving a predetermined wavelength from the light 128 emitted by thelight source 126 to the tank 112. The photoinitiator is preferablyselected based on the wavelength of the light 128 emitted by the lightsource 126.

As shown in FIG. 3 , the printed object 122 is formed on the surface120A of the rigid base 120. The printed object 122 is based on a modelsupplied to a computer (now shown) that controls the 3D printingprocess. The light 128 emitted from the light source 126 is guided tothe tank 112 to cure the liquid polymer resin 130 on the surface 120A ofthe rigid base 120 to form a first layer of the printed object 122. Thecontrol arm 124 is connected to the rigid base 120 to move the rigidbase 120 relative to the tank 112 in a direction away from the opticallytransparent window 132A of the base 132. The rigid base 120 is moved adistance approximately equal to a thickness of the formed layer. Thelight 128 is emitted from the light source 126 to cure the liquidpolymer resin 130 in the tank 112 to form a second layer on the firstlayer. This process is repeated until the entire object is printed. Whenthe printing is complete, the printed object 122 can be removed from theprint surface 120A of the rigid base 120.

As shown in FIG. 3 , the textured surface 114 is connected to the tank112. The textured surface 114 is preferably at least disposed on theoptically transparent window 132A of the base 132. The textured surface114 is configured such that the light 128 emitted by the light source126 passes through the textured surface 114 to the liquid polymer resin130 in the tank 112. The base 132 has an outer surface 132B that facesthe light source 126 and an inner surface 132C that faces the liquidpolymer resin 130 and the build plate 120. The textured surface 114 isformed on the inner surface 132C of the optically transparent window132A facing the liquid polymer resin 130.

Referring to FIG. 3 , the textured surface 114 is formed integrally withthe base 132 of the tank 112. In other words, the textured surface 114is the surface of the optically transparent window facing the liquidpolymer resin 130. The textured surface 114 includes a plurality ofprotrusions 136 extending upwardly from the inner surface 132C of thebase 132. The plurality of protrusions 136 form a plurality of rowsextending in a length direction L of the base 132, and a plurality ofcolumns extending in the width direction W of the base 132, as shown inFIGS. 6 and 15 . Each protrusion 136 is preferably equally spaced fromadjacent protrusions 136 in the row by a distance L1. Each protrusion136 is preferably equally spaced from adjacent protrusions 136 in thecolumn by a distance W1. Preferably, the distances L1 and W1 aresubstantially equal. The projections 136 are enlarged for visualizationin the drawing figures. Preferably, the projections 136 measure a fewmicrons or sub-microns in the x, y and z directions. For example, thetextured surface 114 can include projections 136 measuring 10×10×10microns.

As shown in FIGS. 3 and 5-7 , the protrusions have a substantiallyrectangular shape. The protrusions 136 increase the surface area of theinner surface 132C of the base 132 to increase heat dissipation of theheat generated during light radiation and resin polymerization. In otherwords, the protrusions 136 act like a heat sink to facilitate heatdissipation. As shown in FIG. 5 , heat 152 generated during the lightradiation and resin polymerization is dissipated from tank 112 throughthe textured surface 114.

The textured surface 114 can be fabricated in any suitable manner, suchas by photolithography, laser texturing, molding, or any other suitablepatterning technique. The textured surface 114 can be further treatedwith a hydrophobic layer 180 to produce a hydrophobic orsuperhydrophobic surface, as shown in FIG. 14 . The treated hydrophobicor superhydrophobic surface provides a thermodynamically favorablecondition for impregnation by a layer of an inert liquid 146. Forexample, the textured surface 114 is formed of fused silica, which istreated with the hydrophobic layer 180 of silane to provide ahydrophobic textured surface. The textured surface 114 can be formed ofany suitable optically transparent material. The hydrophobic layer 180can be any suitable material to provide a hydrophobic orsuperhydrophobic surface to the textured surface 114.

As shown in FIGS. 3, 6 and 7 , the first transducer 116 is mounted on aninterior surface of the tank 112. Preferably, the first transducer 116is mounted on the inner surface 132C of the base 132. Alternatively, thefirst transducer 116 can be mounted on an inner surface 134A of the wall134. As shown in FIG. 3 , the first transducer 116 is mounted on theinner surface 132C of the base 112 and on the inner surface 134A of thewall 134 of the tank 112. The first transducer 116 is mounted at aheight of the textured surface 114. The tank 112 is substantiallyrectangular as shown in FIG. 6 , such that the first transducer 116 isdisposed on a first wall 134B that is oppositely disposed a second wall134C on which the second transducer 138 is disposed.

As shown in FIGS. 3, 6 and 7 , a second transducer 138 is connected tothe tank 112 and is configured to emit a second acoustic wave 140 towardthe textured surface 114. The second transducer 138 is disposed oppositethe first transducer 116. The second transducer 138 is preferablydisposed at approximately the same height relative to the base 132 ofthe tank 112 as the first transducer 116.

A first heat exchanger 142 is connected to the tank 112, as shown inFIGS. 3, 6 and 7 . The first heat exchanger 142 is configured to coolthe liquid polymer resin 130. The first heat exchanger 142 is preferablymounted on an outer surface 134D of the wall 134 of the tank 112. Thefirst heat exchanger 142 is preferably mounted to the same wall 134 towhich the first transducer 116 is mounted. The first heat exchanger 142is preferably mounted proximate the first transducer 116. The first heatexchanger 142 is preferably mounted higher than the first transducer 116relative to the base 132 of the tank 112. In other words, the first heatexchanger 142 is preferably mounted higher than the first transducer 116relative to the transparent window 132A of the tank 112. The firsttransducer 116 is preferably disposed such that at least a portion ofthe first transducer 116 is lower than an upper surface 130A of theliquid polymer resin 130 in the tank 112, as shown in FIGS. 3 and 7 .

As shown in FIGS. 3, 6 and 7 , a second heat exchanger 144 is connectedto the tank 112. The second heat exchanger 144 is configured to cool theliquid polymer resin 130. The second heat exchanger 144 is preferablymounted on an outer surface 134D of the wall 134 of the tank 112. Thesecond heat exchanger 144 is preferably mounted to the same wall 134 towhich the second transducer 138 is mounted. The second heat exchanger144 is preferably mounted proximate the second transducer 138. Thesecond heat exchanger 144 is preferably mounted higher than the secondtransducer 138 relative to the base 132 of the tank 112. In other words,the second heat exchanger 144 is preferably mounted higher than thesecond transducer 138 relative to the transparent window 132A of thetank 112.

The first and second heat exchangers 142 and 144 can be any suitableheat exchangers. The first and second heat exchangers 142 and 144 can bepassive or active heat exchangers that facilitate extracting andremoving heat from the liquid polymer resin 130 in the tank 112generated by the emitted light 128 and the photopolymerization processof printing the printed object 122. The first and second heat exchangers142 and 144 can include a peltier module to facilitate removing heatfrom the liquid polymer resin 130. Alternatively, the first and secondheat exchangers 142 and 144 can be mounted on an inner surface 134A ofthe wall 134 of the tank 112. Alternatively, the heat exchangers can beimplemented into the textured surface 114 to provide direct cooling ofthe printing region in an active or passive manner. Alternatively, theheat exchangers can be passively or actively circulated by a coolingradiator to facilitate transferring cooler resin from an upper end ofthe tank 112 to a lower end of the tank 112. A temperature sensor (notshown) can be disposed in the liquid polymer resin 130 in the tank 112to monitor the temperature of the resin 130 such that he first andsecond heat exchangers 142 and 144 can be controlled to maintain theliquid polymer resin 130 at a predetermined temperature.

A layer of an inert liquid 146 is disposed on the textured surface 114,as shown in FIGS. 3 and 5-7 . The inert liquid 146 facilitatespreventing adhesion between the liquid polymer resin 130 and thetextured surface 114. The inert liquid 146 is preferably disposed aboveupper surfaces 136A of the projections 136 of the textured surface 114.A refractive index of the inert liquid 146 is approximately equal to arefractive index of the textured surface 114. Referring to FIG. 12 ,substantially matching the refractive indices of the inert liquid 146and the textured surface 114 minimizes diffraction of the light 128emitted by the light source 126 (FIG. 3 ) to facilitate maintainingprinting resolution. The inert liquid 146 is preferably immiscible andnon-reactive with the liquid polymer resin 130. Preferably, the inertliquid 146 has a higher density than the liquid polymer resin 130 tofacilitate the inert liquid 146 being disposed between the texturedsurface 114 and the liquid polymer resin 130. The inert liquid 146 canbe any suitable liquid, such as perfluoropolyether copolymers,fluorosilicone polymers, perfluorocarbon liquid, gallicin or garlicoils, Chemours Krytox GPL oil, and Solvay Fomblin Y oil.

The emitted light 128 (FIG. 3 ) passing through the layer of the inertliquid 146 exhibits minimal attenuation, such that the transmitted powerof the emitted light is substantially not reduced. The resulting 3Dprinting process is energy efficient such that high-speed fabrication ofparts is possible with the 3D printing process in accordance with theexemplary embodiments. Existing methods to prevent resin adhesion duringthe printing process, such as forming a resin dead zone between thetransparent window and the printed part, results in problematic lightattenuation, which reduces the transmitted power of the emitted lightand greatly reduces the obtainable printing speed of the existing 3Dprinting systems.

Referring to FIGS. 3, 5, 6 and 7 , the first and second transducers 116and 138 are mounted to the inner surface 134A of the wall 134 of thetank 112 and the first and second heat exchangers 142 and 144 aremounted to the outer surface 134D of the wall 134 of the tank 134. Thefirst and second transducers 116 and 138 are oppositely disposed. Thefirst and second heat exchangers 142 and 144 are oppositely disposed.The first and second heat exchangers 142 and 144 are disposed above thefirst and second transducers 116 and 138 relative to the opticallytransparent window 132A of the base 132.

As shown in FIGS. 3 and 5 , the first and second heat exchangers 142 and144 extract heat 154 from the resin 130. Removing the heat cools theliquid polymer resin 130, which increases the density of the resin 130.As indicated by the flow arrows 150 and 151, the increased density ofthe liquid polymer resin 130 proximal the first and second heatexchangers 142 and 144 imparts a downward flow of the resin 130. Thefirst and second heat exchangers 142 and 144 are configured to cool theliquid polymer resin 130 in the tank 112 to facilitate flow of theliquid polymer resin 30 toward the first and second transducers 116 and138, respectively. The wall 134 of the tank 112 is heat dissipative tofacilitate removing the heat 154 from the liquid polymer resin 130. Thethermal conductivity of the heat dissipative wall 134 of the tankfurther facilitates dissipating heat from the resin 130 as the resinflows downwardly proximal the inner surface 134A of the wall 134, asindicated by the resin flow arrows 150 and 151.

The first and second transducers 116 and 138 emit first and secondacoustic waves 118 and 140, as shown in FIGS. 3 and 5 . Preferably, asshown in FIG. 3 , a first direction of the first acoustic wave 118 issubstantially parallel to a second direction of the second acoustic wave140. The first and second acoustic waves 118 and 140 facilitate guidingthe resin 130 toward the printed object 122.

As shown in FIGS. 3 and 5 , the flow 150 and 151 of the cooled resinflows toward the textured surface 114, and the first and secondtransducers 116 and 138 facilitate guiding the cooled resin toward theprinted object 122. As shown in FIG. 5 , a circular flow 156 is impartedto the resin 130 by the combination of the first and second heatexchangers 142 and 144 and the first and second transducers 116 and 138to facilitate guiding resin to a build area of the printed object 122.The first and second heat exchangers 142 and 144 cool the resin as itflows downwardly proximal the inner surface 134A of the wall 134, andthe textured surface 114 further facilitates cooling the resin 130 as itflows substantially horizontally across the textured surface 114, asindicated by the flow arrows 150 and 151 in FIG. 3 .

Referring to FIG. 13 , the first and second acoustic waves 118 and 140travel through the resin 130 and the inert liquid 146. The portion 174of the acoustic wave generated by the first transducer 116 travelingthrough the inert liquid 146 travels faster than the portion 172 of theacoustic wave generated by the first transducer 116 through the resin130. The faster moving acoustic waves 174 in the inert liquid relativeto the slower moving acoustic waves 172 in the resin 130 generates ashearing effect at the interface between the inert liquid 146 and theliquid polymer resin 130. The generated shearing effect substantiallyprevents adhesion of the liquid polymer resin 130 to the texturedsurface 114 of the optically transparent window 132A.

Further, the first and second transducers 116 and 138 are mounted on aninterior surface 132C of the tank 112 such that the emitted the firstand second acoustic waves 118 and 140 travel through the inert liquidlayer 146 and the liquid polymer resin 130, which generates a shearvibration at the interface between the inert liquid layer 146 and theliquid polymer resin 130 to further facilitate resin flow. The shearvibration further reduces the interfacial friction force at theinterface between the inert liquid layer 146 and the liquid polymerresin 130 to facilitate resin flow.

The layer of the inert liquid 146 is inert to the photopolymerizationreaction occurring during the 3D printing process. The textured surface114 stabilizes the layer of the inert liquid 146 to reduce the shearresistance of the resin flow and to substantially prevent resinadhesion, such that the speed of the 3D printing process is improved.The first and second transducers 116 and 138 control the acoustic energyflow to guide the direction flow of the liquid polymer resin 130, asindicated by the resin flow arrows 150 and 151 in FIGS. 3 and 156 inFIG. 5 . The first and second transducers 116 and 138 further facilitatecontrolling the resin flow to improve the speed of the 3D printingprocess. The first and second heat exchangers 142 and 144, in additionto the textured surface 114, further improve controlling the resin flowby removing heat from the resin. The textured surface 114 scatters theincident acoustic waves to further facilitate resin flow toward therigid base 120.

As shown in FIG. 4 , a 3D printing system and method 210 in accordancewith another illustrated exemplary embodiment is substantially similarto the 3D printing system and method 110 of the exemplary embodimentillustrated in FIGS. 3 and 5-7 except for the differences describedbelow. Similar parts are identified with similar reference numerals,except increased by 100 (i.e., 2xx, accordingly).

The 3D printing system 210 illustrated in FIG. 4 includes a texturedsurface 214 that is an insert 219 in the tank 212. The textured surface214 is made of an optically transparent material that overlies theoptically transparent window 232A of the base 232 such that the light228 emitted by the light source 226 passes through the window 232A andthe textured surface 214 into the liquid polymer resin 230 to form aprinted object 222 on the rigid base 220. The insert 219 is disposedadjacent the optically transparent window 232A. The textured surface 214is the surface of the insert 219 facing the liquid polymer resin 230.The insert 219 can be easily replaced when the textured surface 214deteriorates with time and use.

Alternatively, the insert 219 can include the base 232 of the tank 212.In other words, the insert 219 is connected in an opening defined by thewall 234 of the tank 212.

As shown in FIGS. 8 and 9 , a 3D printing system and method 310 inaccordance with another illustrated exemplary embodiment issubstantially similar to the 3D printing system and method 110 of theexemplary embodiment illustrated in FIGS. 3 and 5-7 except for thedifferences described below. Similar parts are identified with similarreference numerals, except increased by 200 (i.e., 3xx, accordingly).

The first and second transducers 316 and 338 and are mounted on an outersurface of the wall 334 of the tank 312. The first and second heatexchangers 342 and 344 are mounted on the outer surface 334D of the wall334 of the tank 312. The first transducer 316 is disposed above thefirst heat exchanger 342. The second transducer 338 is disposed abovethe second heat exchanger 344. In other words the first heat exchanger342 is mounted lower than the first transducer 316 relative to thetransparent window of the tank 312, and the second heat exchanger 344 ismounted lower than the second transducer 344 relative to the transparentwindow of the tank 312. The first and second transducers 316 and 338 aredisposed above an upper surface of the liquid polymer resin 330 in thetank 330.

The first transducer 316 emits a first acoustic wave 318 toward thetextured surface 314. The second transducer 338 emits a second acousticwave 340 toward the textured surface 314. A non-zero angle α is formedbetween the first direction of the first acoustic wave 318 and a seconddirection of the second acoustic wave 340, as shown in FIG. 8 . Thefirst and second directions of the first and second acoustic waves 318and 340 are not parallel.

The first and second transducers 316 and 338 are disposed above theprotrusions 336 of the textured surface 314 and above the layer of theinert liquid 346. The first and second transducers 316 and 338 arepreferably disposed above an upper surface 330A of the resin 330 in thetank 312.

As shown in FIGS. 10 and 11 , a 3D printing system and method 410 inaccordance with another illustrated exemplary embodiment issubstantially similar to the 3D printing system and method 110 of theexemplary embodiment illustrated in FIGS. 3 and 5-7 except for thedifferences described below. Similar parts are identified with similarreference numerals, except increased by 300 (i.e., 4xx, accordingly).

Referring to FIGS. 10 and 11 , the tank 412 is substantiallyrectangular. A transducer 416 and a heat exchanger 442 are mounted on anouter surface 434D of each of the wall 434. A first transducer 416 ismounted above a first heat exchanger 442 on a first wall 434B. A secondtransducer 438 is mounted above a second heat exchanger 444 on a secondwall 434C. The second wall 434C is disposed opposite the first wall434B. A third transducer 460 is mounted above a third heat exchanger 464on a third wall 434E. A fourth transducer 462 is mounted above a fourthheat exchanger 466 on a fourth wall 434F. The fourth wall 434F isdisposed opposite the third wall 434E. The third transducer isconfigured to emit a third acoustic wave, and the fourth transducer 462is configured to emit a fourth acoustic wave. The third transducer 460is disposed opposite the fourth transducer 462.

The transducers 416, 438, 46A) and 462 emit acoustic waves similarly tothe acoustic waves of the transducers illustrated in FIG. 8 . In otherwords, the acoustic waves emitted by the oppositely disposed transducersform non-zero angles. The transducers emit acoustic waves toward thetextured surface 414.

The first to fourth transducers 416, 438, 460 and 462 are disposed abovethe protrusions 436 of the textured surface 414 and above the layer ofthe inert liquid. The first to fourth transducers 416, 438, 460 and 462are preferably disposed above an upper surface of the resin 430 in thetank 412.

As shown in FIGS. 16 and 17 , a textured surface 514 in accordance withanother illustrated exemplary embodiment is substantially similar to thetextured surface 114 of the 3D printing system and method 110 of theexemplary embodiment illustrated in FIGS. 3 and 5-7 except for thedifferences described below. Similar parts are identified with similarreference numerals, except increased by 400 (i.e., 5xx, accordingly).

Each of the protrusions 536 extends from the inner surface 532C, asshown in FIGS. 16 and 17 . Each protrusion 536 has a substantiallyplanar upper surface 536A. A connecting portion 536B connects an upperportion 536C of the protrusion 536 to the inner surface 532C. Theconnecting portion 536B tapers inwardly to a lower surface 536D of theupper portion 536C of the protrusion 536. The upper portion 536C has asubstantially rectangular cross section.

As shown in FIG. 17 , the inner surface 532C and the protrusions 536 caninclude nanostructures 582. The nanostructures 582 are preferablyhydrophobic, thereby further enhancing the hydrophobicity of thetextured surface 514.

As shown in FIGS. 18 and 19 , a 3D printing system and method 210 inaccordance with another illustrated exemplary embodiment issubstantially similar to the 3D printing system and method 110 of theexemplary embodiment illustrated in FIGS. 3 and 5-7 except for thedifferences described below. Similar parts are identified with similarreference numerals, except increased by 500 (i.e., 6xx, accordingly).

Each of the protrusions 636 extends from the inner surface 632C, asshown in FIGS. 17 and 18 . Each protrusion 636 has a substantiallyplanar upper surface 636A. A connecting portion 636B connects an upperportion 636C of the protrusion 636 to the inner surface 632C. Theconnecting portion 636B has a first portion that tapers inwardly movingaway from the inner surface 632C, and a second portion that tapersoutwardly toward the upper portion 636C. The connecting portion 636B hasa substantially concave outer surface. The upper portion 636C has asubstantially rectangular cross section.

As shown in FIG. 18 , the inner surface 632C and the protrusions 636 caninclude nanostructures 682. The nanostructures 582 are preferablyhydrophobic, thereby further enhancing the hydrophobicity of thetextured surface 614.

As shown in FIG. 20 , a 3D printing system and method 710 in accordancewith another illustrated exemplary embodiment is substantially similarto the 3D printing system and method 110 of the exemplary embodimentillustrated in FIGS. 3 and 5-7 except for the differences describedbelow. Similar parts are identified with similar reference numerals,except increased by 600 (i.e., 7xx, accordingly). The 3D printing systemand method of FIG. 20 can be used with the system and can use any of thefeatures of any of FIGS. 3-19 .

The 3D printing system 710 illustrated in FIG. 20 includes a tank 112containing a liquid photopolymer resin 730. The tank 712 can be anysuitable shape to hold the liquid polymer resin 730 therein, such asrectangular or circular. The tank 712 has a base 732 and a side wall(134, FIG. 5 ) extending upwardly from the base 732. The base 732 ispreferably transparent such that light 728 emitted from a light source726 passes through the base 732. An outer surface 732B of the base 732faces the light source 726 The entirety of the base 732 can betransparent, or a portion of the base 732 can be transparent. Thetransparent portion of the base 732 constitutes an optically transparentwindow 732A through which the light 728 emitted by the light source 726passes.

The 3D printing system 710 illustrated in FIG. 20 further includes atextured surface 714 disposed in a tank 712. The textured surface 714 ismade of an optically transparent material that overlies the opticallytransparent window 732A of the base 732 such that the light 728 emittedby a light source 726 passes through the window 732A and the texturedsurface 714 into the liquid polymer resin 730 to form a printed object722 on a rigid base 720. The textured surface can be hydrophobic oromniphobic.

The textured surface 714 can be an insert 719 disposed adjacent theoptically transparent window 732A, as shown in FIG. 20 . The texturedsurface 714 is the surface of the insert 719 facing the liquid polymerresin 730. The insert 719 can be easily replaced when the texturedsurface 714 deteriorates with time and use. The insert 719 can be madeof any suitable material, such as polydimethylsiloxane (PDMS).

Alternatively, the insert 719 can include the base 732 of the tank 712.In other words, the insert 719 is connected in an opening defined by awall of the tank 712.

Alternatively, the textured surface 714 can be etched onto a surface ofthe optically transparent window facing the liquid polymer resin 730, asshown in FIG. 3 .

A layer of an inert material 746 is disposed on the textured surface714, as shown in FIG. 20 . The inert material 746 facilitates preventingadhesion between the liquid polymer resin 730 and the textured surface714. The inert material 746 is preferably disposed above upper surfaces736A of the projections 736 of the textured surface 714. The resin 730is disposed between the layer of the inert material 746 and the rigidbase 720. The layer of the inert material 746 is inert to thephotopolymerization reaction occurring during the 3D printing process.The inert material 746 is preferably a liquid, a semi-liquid, or asemi-solid, including gels.

The layer of the inert material 746 forms a meniscus between thetextured surface 714 and the resin 730, as shown in FIG. 20 . The inertmaterial 746 provides a slippery surface to facilitate resin flow,including the recoating process, and facilitates smoothing out the curedsurface of the printed object 722 to provide high speed printing andsurface smoothness of the printed object 722. The inert material 746 hasan interfacial energy to strongly adhere to the textures surface 714 andhas a surface tension and interfacial energy with the resin 730 tosupport and hold the resin 730 with minimal interruption in the inertmaterial layer 746. The meniscus formed by the layer of the inertmaterial 746 substantially prevents penetration of the resin 730 intothe inert material layer 746, even when a density of the resin 730 isgreater than a density of the inert material 730. The inert material 746separates and supports the resin 730 from the textured surface 714. Theinert material 746 is substantially uniform across the entire plane, asshown in FIG. 20 , such that the surface 722A of the printed object 722can be smoothly formed. The light 728 emitted by the light source 726cures the resin 730 substantially immediately after passing through theinert material layer 746, such that the attenuation of the emitted light728 is minimized to provide a sharper image to the resin 730 andimproving the printing resolution.

An upper surface 746A of the inert material 746 is spaced apredetermined distance D1 above an uppermost surface 736A of theprojections 736 of the textured surface 736. The predetermined distanceD1 is preferably between approximately one to ten microns, inclusive. Apredetermined distance D2 from the surface 714A of the textured surface714 to a lower surface 722A of the printed object 722 (the surface 720Aof the rigid base 720 prior to initiating the printing process) ispreferably between 1 to 500 microns, inclusive.

A refractive index of the inert material 746 is approximately equal to arefractive index of the textured surface 714. Substantially matching therefractive indices of the inert material 746 and the textured surface714 minimizes diffraction of the light 728 emitted by the light source726 to facilitate maintaining printing resolution, as shown in FIG. 12 .The inert material 746 is preferably immiscible and non-reactive withthe liquid polymer resin 730. Preferably, the inert material 746 has ahigher density than the liquid polymer resin 730 to facilitate the inertmaterial 746 being disposed between the textured surface 714 and theliquid polymer resin 730, although the inert material 746 can have adensity lower than a density of the resin 730. The inert material 746can be any suitable liquid, such as silicone/polydimethylsiloxanepolymer oils, perfluoropolyether copolymers, fluorosilicone polymers,perfluorocarbon liquid, gallicin or garlic oils, Chemours Krytox GPLoil, and Solvay Fomblin Y oil, or any suitable semi-liquid, orsemi-solid, including gels.

The inert material 746 preferably does not mix with the resin 730. Theinert material 746 preferably is any suitable material having a lowviscosity, a low surface tension, and high density. The inert material746 has any suitable viscosity, preferably between approximately 5 cps(centipoise) and 131 cps, inclusive. The inert material 746 can have anysuitable surface tension, preferably between approximately 19 dynes/cm(centimeter) and 19.7 dynes/cm, inclusive. The inert material 746 canhave any suitable density, preferably between approximately 0.913grams/square centimeter and 1.9 grams/square centimeter, inclusive.

A control arm 724 is connected to the rigid base 720 to control movementand positioning of the rigid base 720 during the printing process. Thecontrol arm 724 is connected to the rigid base 720 to move the rigidbase 720 relative to the tank 712. The control arm 724 preferably hassix degrees of freedom, such that the rigid base 720 can move through acurvilinear path to more accurately print the object 722. The controlarm 124 is preferably a robotic arm having six degrees of freedom alongthe three axes (i.e., the X, Y and Z axes), and rotation about each ofthe three axes (i.e., pitch, roll and yaw).

The projections 736 can have any suitable size and shape. As shown inFIGS. 15 and 20 , the projections 736 are substantially rectangular andhave a dimension A1 of approximately 10 micros in the x-direction, adimension A2 of approximately 10 microns in the y-direction, and adimension of approximately 10 microns in the z-direction. A distance A3between each of the projections 736 is approximately 10 micros.

The layer of the inert material 746 minimizes power loss of the light728 emitted by the light source 726 by minimizing light diffractionthrough the textured surface 714. The 3D printing system 710 does notinclude an unpolymerized resin area, or dead zone, such that the emittedlight 728 substantially immediately cures the resin 730 after passingthrough the layer of the inert material 746 to provide a continuous,high-speed printing process. As the control arm 724 continuously movesthe rigid base in the y-direction indicated by arrow 722B, as shown inFIG. 20 , the resin 730 flows from a first area 730A to a second area730B and into a curing area 730C. The layer of the inert material 746provides a slippery liquid interface to facilitate the flow of resin 730from the first area 730A to the second area 730B and into the curingarea 730C, further facilitating a continuous, high-speed printingprocess. The printing process in accordance with the embodiments of thepresent invention can obtain a linear printing speed of 667microns/second or 2.4 m/hr.

The layer of the inert material in addition to the acoustic wave emittedby the transducer in accordance with the disclosure substantiallyprevents resin adhesion during the 3D printing process to eliminate theup and down motion of the rigid base performed in existing 3D printingprocesses. The acoustic waves emitted by the transducer in addition tothe resin cooling provided by the heat exchanger in accordance with thedisclosure facilitates resin flow to improve 3D printing speed. Thelayer of the inert material between the textured surface and the resinin accordance with the disclosure further facilitates continuous,high-speed printing. The provided resin cooling allows continuous, largevolumetric 3D printing by minimizing the effects associated with thermalcuring caused by over-heated resin.

General Interpretation of Terms

In understanding the scope of the present invention, the term“comprising” and its derivatives, as used herein, are intended to beopen ended terms that specify the presence of the stated features,elements, components, groups, integers, and/or steps, but do not excludethe presence of other unstated features, elements, components, groups,integers and/or steps. The foregoing also applies to words havingsimilar meanings such as the terms, “including”, “having” and theirderivatives. Also, the terms “part,” “section,” “portion,” “member” or“element” when used in the singular can have the dual meaning of asingle part or a plurality of parts.

The term “detect” as used herein to describe an operation or functioncarried out by a component, a section, a device or the like includes acomponent, a section, a device or the like that does not requirephysical detection, but rather includes determining, measuring,modeling, predicting or computing or the like to carry out the operationor function.

The term “configured” as used herein to describe a component, section orpart of a device includes hardware and/or software that is constructedand/or programmed to carry out the desired function.

The terms of degree such as “substantially”. “about” and “approximately”as used herein mean a reasonable amount of deviation of the modifiedterm such that the end result is not significantly changed.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. For example, the size, shape, location ororientation of the various components can be changed as needed and/ordesired. Components that are shown directly connected or contacting eachother can have intermediate structures disposed between them. Thefunctions of one element can be performed by two, and vice versa. Thestructures and functions of one embodiment can be adopted in anotherembodiment. It is not necessary for all advantages to be present in aparticular embodiment at the same time. Every feature which is uniquefrom the prior art, alone or in combination with other features, alsoshould be considered a separate description of further inventions by theapplicant, including the structural and/or functional concepts embodiedby such feature(s). Thus, the foregoing descriptions of the embodimentsaccording to the present invention are provided for illustration only,and not for the purpose of limiting the invention as defined by theappended claims and their equivalents.

What is claimed is:
 1. A 3D printing system comprising: a tankcontaining a liquid photopolymer resin; a textured surface disposed inthe tank and through which light is configured to pass into the liquidpolymer resin; and a layer of an inert material disposed on the texturedsurface.
 2. The 3D printing system according to claim 1, wherein thetank includes an optically transparent window through which the light isconfigured to pass.
 3. The 3D printing system according to claim 2,wherein the textured surface is etched onto a surface of the windowfacing the inert material.
 4. The 3D printing system according to claim2, wherein an insert is disposed adjacent the optically transparentwindow, the textured surface being a surface of the insert facing theinert material.
 5. The 3D printing system according to claim 1, whereinthe insert is made of polydimethylsiloxane.
 6. The 3D printing systemaccording to claim 1, wherein an upper surface of the inert material isspaced a predetermined distance above an uppermost surface of thetextured surface.
 7. The 3D printing system according to claim 6,wherein the predetermined distance is between approximately one to tenmicrons, inclusive.
 8. The 3D printing system according to claim 1,wherein the textured surface is hydrophobic.
 9. The 3D printing systemaccording to claim 1, wherein a refractive index of the inert materialis approximately equal to a refractive index of the textured surface.10. The 3D printing system according to claim 1, wherein the inertmaterial has a viscosity between approximately 5 cps and 131 cps,inclusive.
 11. The 3D printing system according to claim 1, wherein theinert material has a surface tension between approximately 19 dynes/cmand 19.7 dynes/cm, inclusive.
 12. The 3D printing system according toclaim 1, wherein the inert material has a density between approximately0.913 grams/square centimeter and 1.9 grams/square centimeter,inclusive.
 13. A 3D printing system comprising: a tank containing aliquid photopolymer resin; a rigid base on which an object is configuredto be printed; a textured surface disposed in the tank and through whichlight is configured to pass into the liquid polymer resin; and a layerof an inert material disposed on the textured surface, the resin beingdisposed between the layer of the inert material and the rigid base. 14.The 3D printing system according to claim 13, wherein the tank includesan optically transparent window through which the light is configured topass.
 15. The 3D printing system according to claim 14, wherein thetextured surface is etched onto a surface of the transparent windowfacing the inert material.
 16. The 3D printing system according to claim14, wherein an insert is disposed adjacent the optically transparentwindow, the textured surface being a surface of the insert facing theinert material.
 17. The 3D printing system according to claim 16,wherein the insert is made of polydimethylsiloxane.
 18. The 3D printingsystem according to claim 13, wherein the textured surface ishydrophobic.
 19. The 3D printing system according to claim 13, wherein arefractive index of the inert material is approximately equal to arefractive index of the textured surface.
 20. The 3D printing systemaccording to claim 1, wherein an upper surface of the inert material isspaced a predetermined distance above an uppermost surface of thetextured surface.